support suspend to ram. So needs this for preventing
build error on them.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
—